1. Field of the Invention
The present invention relates to a recording material determination apparatus determining a type of recording material, and an image forming apparatus with the recording material determination apparatus mounted thereon.
2. Description of the Related Art
Some of conventional image forming apparatuses such as copiers or laser printers include a sensor for determining a type of recording material therein. The sensor is used to determine a type of recording material, and image forming conditions such as a transfer condition and/or a fixing condition are set according to the determination result.
A recording material determination apparatus using an ultrasonic wave is proposed as one of the methods for determining a type of recording material. In Japanese Patent Application Laid-Open No. 2004-107030, a type of recording material is determined by emitting an ultrasonic wave to the recording material, receiving an ultrasonic wave reflected from the recording material, and measuring a reflectance of the ultrasonic wave reflected from the recording material. Further, there is discussed a method for determining the thickness of a recording material by receiving an ultrasonic wave transmitted through the recording material and measuring a transmittance of the ultrasonic wave transmitted through the recording material.
In addition, Japanese Patent Application Laid-Open No. 2004-219856 discusses a method for detecting a surface property of a recording material by receiving an ultrasonic wave transmitted through the recording material and determining a transmittance of the recording material.
However, while the method of Japanese Patent Application Laid-Open No. 2004-219856 can detect a surface property of the recording material at one point, there is a possibility that the detection result will not be suitable as the detection result over the entire recording material. In general, a surface property or a grammage is not uniform over the entire recording material but is uneven in the recording material. Therefore, there is a possibility that the detection result at one point of the recording material will not be equal to the detection result over the entire recording material.